Re: Mapping operations to codes
On 8/23/2011 3:30 PM, Default User wrote:
"Victor Bazarov"<v.bazarov@comcast.invalid> wrote in message
news:j30pb0$1pi$1@dont-email.me...
The maps don't seem to be needed per instance of class ('test') but rather
per class (i.e. they should probably be static). That's all I have so
far. I would probably try rewriting the code so that 'write' and 'list'
functions were static as well.
I fear I haven't given enough information, and my example was too sketchy.
1. There will be a number of different drivers, one for each instrument, all
of with derive from the base class.
That's your design. That's not the problem definition, though.
2. The driver objects will be contained by other, higher-level ones. These
higher level "device" modules are derived from a common base class
themselves.
OK. A device consists of (or contains) a collection of drivers. Let's
go with that.
> That base class has a pointer to the driver base class.
A *single* pointer? How does that work with the collection (see above)?
> The
derived class objects will populate that pointer with the particular driver
that they need.
A single pointer? Is that some kind of an "active" driver? From where
do those get populated? Is there a repository of driver objects?
3. The "device" objects will call the small set of public methods using
polymorphism.
Whose methods? Driver's?
> Some methods are in the base class, others specific to a
particular device. Mostly these route op codes and data to the driver, or
retrieve data pulled from the instrument.
"The" instrument? The "active" one? There is only one instrument at a
time? Can there be the need to retrieve data from a driver/instrument
that is not active?
4. The drivers will have class attributes that contain state information
about the particular instrument associated with the driver. The op code
handlers can't be static. Here my example really failed. Mentally add
several attributes, if you would.
You're explaining your design instead of explaining the problem. Can
one device have drivers that serve the same operation? If not, then
each driver (op server or whatever you decide to call it) is unique at
the *device* level, and there seems to be no sense to map its operation
to its function at the level of the *driver*. Place a master map at the
device level.
V
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